The fabrication of cast restorations involves numerous technique-sensitive procedures for the attainment of accurately fitting restorations. Marginal fit has been identified as a cause of failure of cast restorations. Accurate marginal fit and proper contour and surface finish of a crown are critical to maintain a healthy contiguous gingiva.
Unsealed margins can potentially be an entry point for microorganisms, resulting in accumulation of acids and debris, leading inevitably to recurrent caries. A resin-based cement, that is less soluble in the mouth than most other cements, can achieve such a seal. With the use of these newer resin-based and resin ionomer cements, removal of excess material extruding from margins after placement of dental constructs such as crowns, inlays, onlays or veneers, can be difficult and often incomplete when the cement is allowed to polymerize completely, since at that stage they are extremely hard. Especially access to interproximal surfaces is difficult, potentially leaving practically insoluble remnants of cement in areas that are difficult to clean and therefore prone to periodontal disease. When using resin or resin ionomer cements it is therefore beneficial to the practitioner to remove the cement before it sets, or during the gel or initial setting phase, making this step an easier and more predictable procedure. It was speculated that the technique of cement removal has a direct effect on the marginal configuration and seal of the interface preparation/restoration.
The present invention provides a technique for the removal of resin or resin ionomer dental cements that yields improved marginal adaptation and a good marginal seal. Ideal or acceptable margins were defined as margins being continuous with the emergence profile of tooth and restoration. In addition dye penetration followed by sectioning of cemented restorations was used to evaluate the quality of the marginal seal.